01 - Preheat oven to 375°F. Lightly grease a 9x13 inch baking dish with cooking spray or a small amount of oil.
02 - In a large mixing bowl, combine shredded chicken, 1 cup enchilada sauce, black beans, corn, diced red onion, cumin, chili powder, garlic powder, salt, and pepper. Mix thoroughly until all ingredients are evenly distributed.
03 - Spread 1/2 cup of enchilada sauce evenly across the bottom of the prepared baking dish.
04 - Arrange four tortillas over the sauce, overlapping slightly and tearing as necessary to completely cover the bottom of the dish.
05 - Distribute half of the chicken mixture evenly over the tortillas. Sprinkle with 2/3 cup of shredded Mexican cheese blend.
06 - Place another layer of tortillas over the cheese. Top with remaining chicken mixture and another 2/3 cup of shredded cheese.
07 - Arrange the final tortilla layer on top. Pour the remaining 1/2 cup enchilada sauce evenly over the surface. Top with remaining cheese and sliced black olives if desired.
08 - Cover the baking dish tightly with aluminum foil. Bake for 20 minutes to allow flavors to meld and ingredients to heat through.
09 - Remove foil and continue baking for an additional 10 minutes, or until cheese is bubbly and lightly golden brown on top.
10 - Let the casserole rest for 5 minutes before serving. Garnish with fresh cilantro, sliced green onions, avocado, sour cream, and lime wedges as desired.